/**
 * @file
 * Multicast listener discovery
 *
 * @defgroup mld6 MLD6
 * @ingroup ip6
 * Multicast listener discovery for IPv6. Aims to be compliant with RFC 2710.
 * No support for MLDv2.\n
 * To be called from TCPIP thread
 */

/*
 * Copyright (c) 2010 Inico Technologies Ltd.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
 * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
 * OF SUCH DAMAGE.
 *
 * This file is part of the lwIP TCP/IP stack.
 *
 * Author: Ivan Delamer <delamer@inicotech.com>
 *
 *
 * Please coordinate changes and requests with Ivan Delamer
 * <delamer@inicotech.com>
 */

/* Based on igmp.c implementation of igmp v2 protocol */

#include "lwip/opt.h"

#if LWIP_IPV6 && LWIP_IPV6_MLD  /* don't build if not configured for use in lwipopts.h */

#include "lwip/mld6.h"
#include "lwip/prot/mld6.h"
#include "lwip/icmp6.h"
#include "lwip/ip6.h"
#include "lwip/ip6_addr.h"
#include "lwip/ip.h"
#include "lwip/inet_chksum.h"
#include "lwip/pbuf.h"
#include "lwip/netif.h"
#include "lwip/memp.h"
#include "lwip/stats.h"

#include <string.h>


/*
 * MLD constants
 */
#define MLD6_HL                           1
#define MLD6_JOIN_DELAYING_MEMBER_TMR_MS  (500)

#define MLD6_GROUP_NON_MEMBER             0
#define MLD6_GROUP_DELAYING_MEMBER        1
#define MLD6_GROUP_IDLE_MEMBER            2

/* Forward declarations. */
static struct mld_group *mld6_new_group(struct netif *ifp, const ip6_addr_t *addr);
static err_t mld6_remove_group(struct netif *netif, struct mld_group *group);
static void mld6_delayed_report(struct mld_group *group, u16_t maxresp);
static void mld6_send(struct netif *netif, struct mld_group *group, u8_t type);


/**
 * Stop MLD processing on interface
 *
 * @param netif network interface on which stop MLD processing
 */
err_t
mld6_stop(struct netif *netif)
{
    struct mld_group *group = netif_mld6_data(netif);

    netif_set_client_data(netif, LWIP_NETIF_CLIENT_DATA_INDEX_MLD6, NULL);

    while (group != NULL)
    {
        struct mld_group *next = group->next; /* avoid use-after-free below */

        /* disable the group at the MAC level */
        if (netif->mld_mac_filter != NULL)
        {
            netif->mld_mac_filter(netif, &(group->group_address), NETIF_DEL_MAC_FILTER);
        }

        /* free group */
        memp_free(MEMP_MLD6_GROUP, group);

        /* move to "next" */
        group = next;
    }
    return ERR_OK;
}

/**
 * Report MLD memberships for this interface
 *
 * @param netif network interface on which report MLD memberships
 */
void
mld6_report_groups(struct netif *netif)
{
    struct mld_group *group = netif_mld6_data(netif);

    while (group != NULL)
    {
        mld6_delayed_report(group, MLD6_JOIN_DELAYING_MEMBER_TMR_MS);
        group = group->next;
    }
}

/**
 * Search for a group that is joined on a netif
 *
 * @param ifp the network interface for which to look
 * @param addr the group ipv6 address to search for
 * @return a struct mld_group* if the group has been found,
 *         NULL if the group wasn't found.
 */
struct mld_group *
mld6_lookfor_group(struct netif *ifp, const ip6_addr_t *addr)
{
    struct mld_group *group = netif_mld6_data(ifp);

    while (group != NULL)
    {
        if (ip6_addr_cmp(&(group->group_address), addr))
        {
            return group;
        }
        group = group->next;
    }

    return NULL;
}


/**
 * create a new group
 *
 * @param ifp the network interface for which to create
 * @param addr the new group ipv6
 * @return a struct mld_group*,
 *         NULL on memory error.
 */
static struct mld_group *
mld6_new_group(struct netif *ifp, const ip6_addr_t *addr)
{
    struct mld_group *group;

    group = (struct mld_group *)memp_malloc(MEMP_MLD6_GROUP);
    if (group != NULL)
    {
        ip6_addr_set(&(group->group_address), addr);
        group->timer              = 0; /* Not running */
        group->group_state        = MLD6_GROUP_IDLE_MEMBER;
        group->last_reporter_flag = 0;
        group->use                = 0;
        group->next               = netif_mld6_data(ifp);

        netif_set_client_data(ifp, LWIP_NETIF_CLIENT_DATA_INDEX_MLD6, group);
    }

    return group;
}

/**
 * Remove a group from the mld_group_list, but do not free it yet
 *
 * @param group the group to remove
 * @return ERR_OK if group was removed from the list, an err_t otherwise
 */
static err_t
mld6_remove_group(struct netif *netif, struct mld_group *group)
{
    err_t err = ERR_OK;

    /* Is it the first group? */
    if (netif_mld6_data(netif) == group)
    {
        netif_set_client_data(netif, LWIP_NETIF_CLIENT_DATA_INDEX_MLD6, group->next);
    }
    else
    {
        /* look for group further down the list */
        struct mld_group *tmpGroup;
        for (tmpGroup = netif_mld6_data(netif); tmpGroup != NULL; tmpGroup = tmpGroup->next)
        {
            if (tmpGroup->next == group)
            {
                tmpGroup->next = group->next;
                break;
            }
        }
        /* Group not find group */
        if (tmpGroup == NULL)
        {
            err = ERR_ARG;
        }
    }

    return err;
}


/**
 * Process an input MLD message. Called by icmp6_input.
 *
 * @param p the mld packet, p->payload pointing to the icmpv6 header
 * @param inp the netif on which this packet was received
 */
void
mld6_input(struct pbuf *p, struct netif *inp)
{
    struct mld_header *mld_hdr;
    struct mld_group *group;

    MLD6_STATS_INC(mld6.recv);

    /* Check that mld header fits in packet. */
    if (p->len < sizeof(struct mld_header))
    {
        /* @todo debug message */
        pbuf_free(p);
        MLD6_STATS_INC(mld6.lenerr);
        MLD6_STATS_INC(mld6.drop);
        return;
    }

    mld_hdr = (struct mld_header *)p->payload;

    switch (mld_hdr->type)
    {
    case ICMP6_TYPE_MLQ: /* Multicast listener query. */
        /* Is it a general query? */
        if (ip6_addr_isallnodes_linklocal(ip6_current_dest_addr()) &&
                ip6_addr_isany(&(mld_hdr->multicast_address)))
        {
            MLD6_STATS_INC(mld6.rx_general);
            /* Report all groups, except all nodes group, and if-local groups. */
            group = netif_mld6_data(inp);
            while (group != NULL)
            {
                if ((!(ip6_addr_ismulticast_iflocal(&(group->group_address)))) &&
                        (!(ip6_addr_isallnodes_linklocal(&(group->group_address)))))
                {
                    mld6_delayed_report(group, mld_hdr->max_resp_delay);
                }
                group = group->next;
            }
        }
        else
        {
            /* Have we joined this group?
             * We use IP6 destination address to have a memory aligned copy.
             * mld_hdr->multicast_address should be the same. */
            MLD6_STATS_INC(mld6.rx_group);
            group = mld6_lookfor_group(inp, ip6_current_dest_addr());
            if (group != NULL)
            {
                /* Schedule a report. */
                mld6_delayed_report(group, mld_hdr->max_resp_delay);
            }
        }
        break; /* ICMP6_TYPE_MLQ */
    case ICMP6_TYPE_MLR: /* Multicast listener report. */
        /* Have we joined this group?
         * We use IP6 destination address to have a memory aligned copy.
         * mld_hdr->multicast_address should be the same. */
        MLD6_STATS_INC(mld6.rx_report);
        group = mld6_lookfor_group(inp, ip6_current_dest_addr());
        if (group != NULL)
        {
            /* If we are waiting to report, cancel it. */
            if (group->group_state == MLD6_GROUP_DELAYING_MEMBER)
            {
                group->timer = 0; /* stopped */
                group->group_state = MLD6_GROUP_IDLE_MEMBER;
                group->last_reporter_flag = 0;
            }
        }
        break; /* ICMP6_TYPE_MLR */
    case ICMP6_TYPE_MLD: /* Multicast listener done. */
        /* Do nothing, router will query us. */
        break; /* ICMP6_TYPE_MLD */
    default:
        MLD6_STATS_INC(mld6.proterr);
        MLD6_STATS_INC(mld6.drop);
        break;
    }

    pbuf_free(p);
}

/**
 * @ingroup mld6
 * Join a group on a network interface.
 *
 * @param srcaddr ipv6 address of the network interface which should
 *                join a new group. If IP6_ADDR_ANY, join on all netifs
 * @param groupaddr the ipv6 address of the group to join
 * @return ERR_OK if group was joined on the netif(s), an err_t otherwise
 */
err_t
mld6_joingroup(const ip6_addr_t *srcaddr, const ip6_addr_t *groupaddr)
{
    err_t         err = ERR_VAL; /* no matching interface */
    struct netif *netif;

    /* loop through netif's */
    netif = netif_list;
    while (netif != NULL)
    {
        /* Should we join this interface ? */
        if (ip6_addr_isany(srcaddr) ||
                netif_get_ip6_addr_match(netif, srcaddr) >= 0)
        {
            err = mld6_joingroup_netif(netif, groupaddr);
            if (err != ERR_OK)
            {
                return err;
            }
        }

        /* proceed to next network interface */
        netif = netif->next;
    }

    return err;
}

/**
 * @ingroup mld6
 * Join a group on a network interface.
 *
 * @param netif the network interface which should join a new group.
 * @param groupaddr the ipv6 address of the group to join
 * @return ERR_OK if group was joined on the netif, an err_t otherwise
 */
err_t
mld6_joingroup_netif(struct netif *netif, const ip6_addr_t *groupaddr)
{
    struct mld_group *group;

    /* find group or create a new one if not found */
    group = mld6_lookfor_group(netif, groupaddr);

    if (group == NULL)
    {
        /* Joining a new group. Create a new group entry. */
        group = mld6_new_group(netif, groupaddr);
        if (group == NULL)
        {
            return ERR_MEM;
        }

        /* Activate this address on the MAC layer. */
        if (netif->mld_mac_filter != NULL)
        {
            netif->mld_mac_filter(netif, groupaddr, NETIF_ADD_MAC_FILTER);
        }

        /* Report our membership. */
        MLD6_STATS_INC(mld6.tx_report);
        mld6_send(netif, group, ICMP6_TYPE_MLR);
        mld6_delayed_report(group, MLD6_JOIN_DELAYING_MEMBER_TMR_MS);
    }

    /* Increment group use */
    group->use++;
    return ERR_OK;
}

/**
 * @ingroup mld6
 * Leave a group on a network interface.
 *
 * @param srcaddr ipv6 address of the network interface which should
 *                leave the group. If IP6_ISANY, leave on all netifs
 * @param groupaddr the ipv6 address of the group to leave
 * @return ERR_OK if group was left on the netif(s), an err_t otherwise
 */
err_t
mld6_leavegroup(const ip6_addr_t *srcaddr, const ip6_addr_t *groupaddr)
{
    err_t         err = ERR_VAL; /* no matching interface */
    struct netif *netif;

    /* loop through netif's */
    netif = netif_list;
    while (netif != NULL)
    {
        /* Should we leave this interface ? */
        if (ip6_addr_isany(srcaddr) ||
                netif_get_ip6_addr_match(netif, srcaddr) >= 0)
        {
            err_t res = mld6_leavegroup_netif(netif, groupaddr);
            if (err != ERR_OK)
            {
                /* Store this result if we have not yet gotten a success */
                err = res;
            }
        }
        /* proceed to next network interface */
        netif = netif->next;
    }

    return err;
}

/**
 * @ingroup mld6
 * Leave a group on a network interface.
 *
 * @param netif the network interface which should leave the group.
 * @param groupaddr the ipv6 address of the group to leave
 * @return ERR_OK if group was left on the netif, an err_t otherwise
 */
err_t
mld6_leavegroup_netif(struct netif *netif, const ip6_addr_t *groupaddr)
{
    struct mld_group *group;

    /* find group */
    group = mld6_lookfor_group(netif, groupaddr);

    if (group != NULL)
    {
        /* Leave if there is no other use of the group */
        if (group->use <= 1)
        {
            /* Remove the group from the list */
            mld6_remove_group(netif, group);

            /* If we are the last reporter for this group */
            if (group->last_reporter_flag)
            {
                MLD6_STATS_INC(mld6.tx_leave);
                mld6_send(netif, group, ICMP6_TYPE_MLD);
            }

            /* Disable the group at the MAC level */
            if (netif->mld_mac_filter != NULL)
            {
                netif->mld_mac_filter(netif, groupaddr, NETIF_DEL_MAC_FILTER);
            }

            /* free group struct */
            memp_free(MEMP_MLD6_GROUP, group);
        }
        else
        {
            /* Decrement group use */
            group->use--;
        }

        /* Left group */
        return ERR_OK;
    }

    /* Group not found */
    return ERR_VAL;
}


/**
 * Periodic timer for mld processing. Must be called every
 * MLD6_TMR_INTERVAL milliseconds (100).
 *
 * When a delaying member expires, a membership report is sent.
 */
void
mld6_tmr(void)
{
    struct netif *netif = netif_list;

    while (netif != NULL)
    {
        struct mld_group *group = netif_mld6_data(netif);

        while (group != NULL)
        {
            if (group->timer > 0)
            {
                group->timer--;
                if (group->timer == 0)
                {
                    /* If the state is MLD6_GROUP_DELAYING_MEMBER then we send a report for this group */
                    if (group->group_state == MLD6_GROUP_DELAYING_MEMBER)
                    {
                        MLD6_STATS_INC(mld6.tx_report);
                        mld6_send(netif, group, ICMP6_TYPE_MLR);
                        group->group_state = MLD6_GROUP_IDLE_MEMBER;
                    }
                }
            }
            group = group->next;
        }
        netif = netif->next;
    }
}

/**
 * Schedule a delayed membership report for a group
 *
 * @param group the mld_group for which "delaying" membership report
 *              should be sent
 * @param maxresp the max resp delay provided in the query
 */
static void
mld6_delayed_report(struct mld_group *group, u16_t maxresp)
{
    /* Convert maxresp from milliseconds to tmr ticks */
    maxresp = maxresp / MLD6_TMR_INTERVAL;
    if (maxresp == 0)
    {
        maxresp = 1;
    }

#ifdef LWIP_RAND
    /* Randomize maxresp. (if LWIP_RAND is supported) */
    maxresp = LWIP_RAND() % maxresp;
    if (maxresp == 0)
    {
        maxresp = 1;
    }
#endif /* LWIP_RAND */

    /* Apply timer value if no report has been scheduled already. */
    if ((group->group_state == MLD6_GROUP_IDLE_MEMBER) ||
            ((group->group_state == MLD6_GROUP_DELAYING_MEMBER) &&
             ((group->timer == 0) || (maxresp < group->timer))))
    {
        group->timer = maxresp;
        group->group_state = MLD6_GROUP_DELAYING_MEMBER;
    }
}

/**
 * Send a MLD message (report or done).
 *
 * An IPv6 hop-by-hop options header with a router alert option
 * is prepended.
 *
 * @param group the group to report or quit
 * @param type ICMP6_TYPE_MLR (report) or ICMP6_TYPE_MLD (done)
 */
static void
mld6_send(struct netif *netif, struct mld_group *group, u8_t type)
{
    struct mld_header *mld_hdr;
    struct pbuf *p;
    const ip6_addr_t *src_addr;

    /* Allocate a packet. Size is MLD header + IPv6 Hop-by-hop options header. */
    p = pbuf_alloc(PBUF_IP, sizeof(struct mld_header) + sizeof(struct ip6_hbh_hdr), PBUF_RAM);
    if (p == NULL)
    {
        MLD6_STATS_INC(mld6.memerr);
        return;
    }

    /* Move to make room for Hop-by-hop options header. */
    if (pbuf_header(p, -IP6_HBH_HLEN))
    {
        pbuf_free(p);
        MLD6_STATS_INC(mld6.lenerr);
        return;
    }

    /* Select our source address. */
    if (!ip6_addr_isvalid(netif_ip6_addr_state(netif, 0)))
    {
        /* This is a special case, when we are performing duplicate address detection.
         * We must join the multicast group, but we don't have a valid address yet. */
        src_addr = IP6_ADDR_ANY6;
    }
    else
    {
        /* Use link-local address as source address. */
        src_addr = netif_ip6_addr(netif, 0);
    }

    /* MLD message header pointer. */
    mld_hdr = (struct mld_header *)p->payload;

    /* Set fields. */
    mld_hdr->type = type;
    mld_hdr->code = 0;
    mld_hdr->chksum = 0;
    mld_hdr->max_resp_delay = 0;
    mld_hdr->reserved = 0;
    ip6_addr_set(&(mld_hdr->multicast_address), &(group->group_address));

#if CHECKSUM_GEN_ICMP6
    IF__NETIF_CHECKSUM_ENABLED(netif, NETIF_CHECKSUM_GEN_ICMP6)
    {
        mld_hdr->chksum = ip6_chksum_pseudo(p, IP6_NEXTH_ICMP6, p->len,
                                            src_addr, &(group->group_address));
    }
#endif /* CHECKSUM_GEN_ICMP6 */

    /* Add hop-by-hop headers options: router alert with MLD value. */
    ip6_options_add_hbh_ra(p, IP6_NEXTH_ICMP6, IP6_ROUTER_ALERT_VALUE_MLD);

    if (type == ICMP6_TYPE_MLR)
    {
        /* Remember we were the last to report */
        group->last_reporter_flag = 1;
    }

    /* Send the packet out. */
    MLD6_STATS_INC(mld6.xmit);
    ip6_output_if(p, (ip6_addr_isany(src_addr)) ? NULL : src_addr, &(group->group_address),
                  MLD6_HL, 0, IP6_NEXTH_HOPBYHOP, netif);
    pbuf_free(p);
}

#endif /* LWIP_IPV6 */
